Upper Extremity Injuries in Youth Baseball:
Causes and Prevention
Biomechanics
Throwing a baseball is an unnatural movement
Excessively high forces are generated at the elbow and shoulder
Throwing requires flexibility, strength, coordination
Biomechanics
Phases of throwing:
Windup Cocking Acceleration Deceleration Follow-through
Biomechanics
Biomechanics
Windup
Body placed in good starting position Gains momentum in forward direction Lasts 0.5 to 1.0 seconds Minimal muscle activity
Biomechanics
Cocking
Begins with front foot contact Ends with shoulder in maximal external rotation
(MER) Elbow flexed, forearm supinated Lasts 0.1 to 0.15 seconds Deltoid, rotator cuff, medial and lateral elbow
musculature highly active during cocking phase
Biomechanics
Acceleration Begins with MER Ends with ball release Arm moves to a position of internal rotation and
adduction at the shoulder and extension at the elbow
Lasts a few hundredths of a second Large valgus and extension forces generated at
the elbow
Biomechanics
Deceleration/Follow-through
Begins with maximal internal rotation (MIR) Ends with foot contact Follow-through is complete when pitcher achieves
a balanced position and is ready to resume play
Shoulder Injuries
Rotator cuff Instability Labral
pathology Little Leaguer’s
shoulder
Rotator Cuff Injuries
Primary impingement Cuff impinging on coracoacromial arch Rare in young athletes
Secondary impingement Due to underlying instability Can result in a poor outcome if instability goes
unrecognized
Rotator Cuff Injuries
Tensile overload Forces generated in cuff during pitching can
cause tendinosis and collagen breakdown
Internal impingement Supraspinatus and infraspinatus contact
posteriosuperior aspect of labrum during MER Caused by chronic compressive damage Results in partial undersurface cuff tear and labral
fraying
Rotator Cuff Injuries - Evaluation History
Specific injury or insidious onset? Pain during cocking usually impingement Pain during deceleration commonly tensile failure
Physical exam AROM/PROM Glenohumeral translation Apprehension/relocation tests ↓ strength due to pain, inhibition, fatigue – rarely
full-thickness tear
Rotator Cuff Injuries - Evaluation
Radiology
Plain films – AP,Y, axillary
MRI
Rotator Cuff Injuries - Treatment
Rest Rehab
Restore ROM Strengthen cuff and
scapular stabilizers Maintain conditioning Throwing program
Anti-inflammatories Surgery
Instability
Stability relies on ligaments and rotator cuff action
Inferior glenohumeral ligament Maximally stretched in external rotation Chronic stretching can cause functional
incompetence Causes rotator cuff to work harder – can fatigue or
tear
Instability - Evaluation
H & P as above Symptoms due to cuff pain or instability?
Signs may be subtle ↓ velocity and early fatigue frequent
complaints Subjective subluxation rare May describe clicking or catching
Instability - Treatment
Rest Rehab
As above, with stretching posterior capsule Surgical stabilization
EUA to determine direction & degree of laxity Correct laxity without compromising motion Subtle laxity → thermal capsulorrhaphy Gross laxity → capsular shift
Labral Pathology
Repetitive microtrauma results in fraying or tearing
Disruption of biceps anchor causes pain and anterior-inferior translation of humeral head when completely detached
Can occur alone, or with instability or cuff pathology
Labral Pathology - Evaluation
H&P as above Pain during acceleration Loss of velocity + O’Brien’s test
Radiology MRI arthrogram most
helpful Dye leaks into tear
Labral Pathology - Treatment
Rest Rehab Surgery
Labral repair Labral debridement
Little Leaguer’s Shoulder
Symptoms
Gradual onset of pain in throwing shoulder Localized to proximal humerus during throwing Average age 14 Average duration of symptoms 8 months
Little Leaguer’s Shoulder
Mechanism Appears to be caused by rotational stress applied
to proximal humeral physis during act of throwing Overuse inflammation of proximal humeral physis
vs. stress fracture of physis During throwing, shoulder is forcibly internally
rotated and adducted from an externally rotated abducted position
Little Leaguer’s Shoulder
Radiology Widening of the proximal humeral physis Easily seen on bilateral AP internal and external
rotation x-rays Associated findings
Demineralization Sclerosis Fragmentation of lateral aspect of proximal humeral
metaphysis
Little Leaguer’s Shoulder - Treatment Rest until symptoms subside with pain-free
ROM Gradual return to throwing when symptoms
subside – remodeling on x-ray can take several months longer
PT usually not beneficial – may have worse pain with strengthening exercises
Elbow Injuries
Little Leaguer’s elbow Ulnar collateral
ligament injuries Loose bodies
Little Leaguer’s Elbow
With repetitive throwing, ligaments and tendons put tension on the end of the bone → causes inflammation of growth plate and ultimately stress fracture
Activity-related pain, tenderness to palpation, decreased pitching effectiveness
Little Leaguer’s Elbow
Treatment
Rest for several weeks until symptoms resolve
Ulnar Collateral Ligament Injuries
Chronic valgus stress places ligament at risk for laxity or tearing
Pitchers at highest risk
UCL Injuries - Evaluation
Medial pain during late cocking, acceleration or deceleration is hallmark
Pain with valgus testing more reliable than laxity
Laxity on valgus testing at 30° minimal unless tear is complete
MRI with contrast – fluid leakage outside of joint represents complete tear
UCL Injuries - Treatment
Rest Physical therapy NSAIDs Return to throwing when pain-free Surgery → autologous tendon secured in
tunnels in humerus and ulna in figure-of-eight fashion, ulnar nerve transposed
Loose Bodies
Mechanism Repetitive throwing causes fragmented cartilage
within joint Directly relates to amount and intensity of
throwing
Loose Bodies
Symptoms Acute activity-related pain Tenderness in outer portion of elbow Decreased ROM Locking or catching in joint
Treatment Rest until symptoms subside Throwing program Continued symptoms → surgery
The Solution…
PITCH LIMIT!!!
Prevents injuries and prolongs careers
“Throwing is not dangerous to a pitcher’s arm. Throwing while tired is dangerous to a pitcher’s arm.” Rany Jazayerli (baseball writer).
Pitch Limit
American Sports Medicine Institute recommends pitches per week: Ages 8-10: 52 pitches Ages 11-12: 68 pitches Ages 13-14: 76 pitches Ages 15-16: 91 pitches Ages 17-18: 106 pitches
Practice and recreational pitching add to this strain
Pitch Types
Pitch type should also be limited to reduce injury
Before age 10, only fast ball and change-up should be permitted
Curveball, slider, knuckleball and screwball may be introduced with increasing age
Pitching Mechanics
Curveball and slider related to joint pain in young pitchers
These pitches place high loads on shoulder and elbow
Curveball requires new set of mechanics Adolescents more susceptible to injury
because growth plates still open
Youth Baseball Recommendations No curveball or slider between 9 and 14 Fastball and change-ups only Age-appropriate pitch limit per game
By adhering to the above recommendations, we can expect the occurrence of shoulder and elbow pain in young throwers to decrease.
Questions?